1. FIELD OF THE INVENTION
The present invention relates to 9-phenylimino-8-thia-1,6-diazabicyclo-[4.3.0]nonane-7-one derivatives useful as herbicides and herbicidal compositions containing them.
2. DISCUSSION OF BACKGROUND
In recent years, a number of herbicides have been developed and actually used, and they have contributed to the reduction of the agricultural work load and to the improvement of the productivity. As a herbicide having a hetero ring, oxadiazon [i.e. 5-t-butyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazoline-2-one] is widely used. However, oxadiazon is likely to bring about phytotoxicity, when used in paddy fields, and it is not effective against perennial weeds, particularly against Sagittaria pygmaea. When used in upland fields, it is not so safe against crop plants such as corn or soybean and has drawbacks that its herbicidal activities are low against hardly controllable seeds such as cocklebur or morning-glory and against pigweed and lambsquaters. Accordingly, a development of a herbicide having improved herbicidal activities and safety has been desired.